1. Field of the Invention
This invention relates to a clamping device, especially for use in well drilling, in particular a stabilizer for a drilling string.
2. Description of the Prior Art
U.S. Pat. No. 4,275,935 discloses a stabilizer for a drill string. The stabilizer is of a split configuration having an open slot which extends for the length of the stabilizer. The split stabilizer is slipped over a drill collar and nuts-and-bolts are used to draw the split stabilizer together to clamp the stabilizer to the drill collar. The stabilizer may thus be positioned at any desired axial location on the drill collar and non-rotatably locked thereto by the nuts-and-bolts. The stabilizer is made in one piece of a non-magnetic metal.
This stabilizer is designed to bear evenly, in its clamped condition, upon a drill collar of a particular diameter around substantially the whole external periphery of the drill collar. However, differences in the external diameters of drill collars of the same nominal diameter can result in a less than optimum bearing of such stabilizer upon a drill collar, so that a desired immobilizing clamping force on the drill collar may not be obtained. To try to meet this difficulty, U.S. Pat. No. 4,275,935 discloses that a shim of cylindrical form having an axially extending split can be utilized between the stabilizer and the collar. However, such a shim cannot cope optimally with a range of diameters and moreover constitutes not only an additional part but also a part that owing to its thinness is easily damaged in the very rough usage to which drilling equipment is normally subjected.
EP0132192, corresponding to U.S. Pat. Nos. 4,611,839 and 4,639,020, discloses a segmented coupling for use in sealing adjacent pipe ends . The coupling includes two semi-circular coupling segments having bolting pads at their ends, the ends of each coupling segment including inclined, planar end faces for cooperation with correspondingly inclined planar end faces of the other coupling segment to produce self-adjustment of the coupling and firmer clamping of the pipe ends upon tightening down of the coupling.
EP0194034, corresponding to U.S. Pat. No. 4653782, discloses a pipe repair clamp of a similar construction.